A former colleague of the author used to maintain that to make a development decision for a new antibacterial, it was necessary to know two things about the compound: its MIC and the achievable blood level. MIC means minimum inhibitory concentration, i.e., the lowest concentration of the inhibitor that gives complete suppression of visible growth in a broth dilution assay (Pratt and Fekety, 1986). This is just one of the hundreds of "rules" that constitute drug development folk-wisdom. Some other examples are (1) no compound with a molecular weight over 1200 will make it as a drug (this one predates the use of recombinant human proteins, though not the use of insulin), (2) to cross the blood-brain barrier a compound has to have log P more positive than —1.5 (log P is the log of the n-octanol-water partition coefficient), and (3) all nitroaromatics are toxic.